- Joined
- Nov 3, 2012
- Messages
- 29
- Reaction score
- 12
I have a 73 Piper arrow and having electrical issues.
1St - Amp meter reads 30-40 amps too high. I know the amp meter is reading too high as I check the current with a clamp amp meter in two places. (1)On the output lead from the alternator and (2)again on the wire just before the connection to the solenoid/battery. Both wires are 6 gauge. Generally 30+ amps difference between the clamp meter and amp meter on the dash. Right after starting the amp is around 60-70 putting on the pitot heat and landing lights amps goes to way above 70 amps. The top of the amp meter on the dash.
2Nd - The master solenoid, next to the battery, seems way too hot. After a short 25 minutes of flying, I landed and touched this solenoid. I could touch it but could not leave my finger on it because it was much to hot.
My thoughts:
1 - The hot solenoid may be due to worn contacts creating higher contact resistance in the master solenoid creating I2R heating. I(squared)R
2 - Secondly if the master solenoid has increased resistance it may influence the dash amp meter. The dash amp meter does not directly measure the total amp put out by the alternator. It measures a portion of the total current. The main wire from the alternator is 6 gauge while the wire to the amp meter is 16. This is a major difference in each wires ability to carry current and each wires total resistance. If there is higher contact resistance in the solenoid it might result in incorrect amp meter readings.
Resistivity per 1000 ft for each wire are:
6 gauge - 0.4 ohms
16 gauge - 4.0 ohms
That is a 10 fold difference between the two wires.
Any thoughts would be greatly appreciated!
Thanks
1St - Amp meter reads 30-40 amps too high. I know the amp meter is reading too high as I check the current with a clamp amp meter in two places. (1)On the output lead from the alternator and (2)again on the wire just before the connection to the solenoid/battery. Both wires are 6 gauge. Generally 30+ amps difference between the clamp meter and amp meter on the dash. Right after starting the amp is around 60-70 putting on the pitot heat and landing lights amps goes to way above 70 amps. The top of the amp meter on the dash.
2Nd - The master solenoid, next to the battery, seems way too hot. After a short 25 minutes of flying, I landed and touched this solenoid. I could touch it but could not leave my finger on it because it was much to hot.
My thoughts:
1 - The hot solenoid may be due to worn contacts creating higher contact resistance in the master solenoid creating I2R heating. I(squared)R
2 - Secondly if the master solenoid has increased resistance it may influence the dash amp meter. The dash amp meter does not directly measure the total amp put out by the alternator. It measures a portion of the total current. The main wire from the alternator is 6 gauge while the wire to the amp meter is 16. This is a major difference in each wires ability to carry current and each wires total resistance. If there is higher contact resistance in the solenoid it might result in incorrect amp meter readings.
Resistivity per 1000 ft for each wire are:
6 gauge - 0.4 ohms
16 gauge - 4.0 ohms
That is a 10 fold difference between the two wires.
Any thoughts would be greatly appreciated!
Thanks